Several attempts have been made to produce rubber-modified asphalt emulsions having the highly desirable properties of stability and prolonged high-level resistance to water-, fuel-, and ultraviolet (UV) light-associated degradation.
Specifically, for example, U.S. Pat. No. 5,492,561 (Flanigan) and U.S. Pat. No. 5,583,168 (Flanigan) describe processes for liquefying tire rubber in a TRMACS process, by heating crumb rubber and asphalt to temperatures of approximately 500° F. U.S. Pat. No. 5,539,029 (Burress) describes a method for preparing an asphalt emulsion comprising mixing aggregate with an aqueous emulsion comprising water, asphalt, a thickening agent, latex rubber, and rubber particles. U.S. Pat. No. 7,087,665 (Sylvester), U.S. Pat. App. No. 2005/0131113, filed Feb. 7, 2005 (Sylvester), and U.S. Pat. App. No. 2007/2049762, filed Jul. 10, 2006 (Sylvester) describe methods for preparing asphalt emulsions comprising mixing a rubber-modified asphalt cement with aqueous solutions comprising an emulsifier.
Although several achievements have been made in producing asphalt emulsions having desirable properties, a need still remain for improved rubber-modified asphalt cement emulsions that possess superior stability and shielding properties.
The present invention provides such an improved emulsion, as well as methods for preparing and using such an emulsion.